Heartbeat Cycle
by benedictcumonmybaps
Summary: AU; Castiel is a chemistry teacher who starts to fall for the new P.E. teacher. Just fluff!


Castiel sat at the far end of the break room, silently watching the other teachers laugh and converse as he absently worked at a leftover half of a burger he'd brought from home. It was lunch, and he'd found that some teachers came into the break room to relax and talk to their colleagues before getting back to the harrowing job they had acquired. At the beginning of the year he had remained in his classroom, having no reason to leave; however, it was when the new P.E. teacher arrived that he began taking his lunches in the break room with the other faculty members.

Mr. Dean Winchester was only slightly taller than him, with cropped brown hair and the most stunning green eyes Castiel had ever seen. They had been introduced, once; when the teachers had their own meet and greet he had shook the man's hand, watched him smile politely, then never spoken to him again. Well, never at length, in any case. There was the occasional greeting. He had felt…something, at the time, a feeling that only managed to grow as he spent his time idling in the break room. He had watched Dean laugh and chat with the others - mostly female teachers, he'd noted – but he would always catch the man glancing over, giving him a look that Castiel still couldn't solve. Maybe it was neutral, he had thought; though maybe, just possibly, it meant something more.

"Castiel?"

He looked up, eyebrows furrowing slightly in confusion when he saw who had called his name.

"Yes?" he asked. They apparently were now on a first-name basis, though something held him back from saying Dean's name. Maybe it was nerves.

"No need to look angry," Dean said with a smirk, sitting across from Castiel at the small foldable table. Cas paused. Did he really look angry? It wasn't purposeful; now that he thought about it, though, he had been told before that he had a very serious demeanor. Perhaps that was what Dean was referring to.

"I'm…not," Castiel started awkwardly, setting his relatively untouched burger down. "I was only thinking."

"During lunch? Jesus, you never stop, do ya," Dean continued, munching on some chips he'd probably gotten from the vending machine that sat in the far corner of the room. Castiel didn't know how to answer, so he didn't, glancing down at his food instead. He felt some odd fuzziness pool in his stomach, his insides seeming to twist into knots. He couldn't remember when he'd felt this before, if he'd felt this before. It was odd and intriguing, like some sort of new problem he could work on. Perhaps an equation would warrant the situation… "You're doing it again."

"I'm sorry," Castiel said, his deep blue eyes again settling on the figure across from him. Maybe he just suffered from heart palpitations…but that was a silly thought. He had no problematic medical history. "Did you say something?"

"I asked why you were in the break room all the damn time," Dean hummed, eyeing the relatively untouched burger sitting abandoned in front of him. Castiel shrugged, lifting a pale hand to gently slide the to-go box over to the other side of the table. Dean gave him a smile in gratitude.

"I see no reason why I shouldn't be here," he said, quickly licking the back of his cracked lips. "…there is coffee." It was lame excuse, and Dean seemed to notice, as he heard a soft chuckle emanate from across the table.

"Sure it's not to see me?"

Castiel froze, his eyes wide as he watched Dean so casually start in on his burger. How could he ask such a thing and act so nonchalant about it? It was disconcerting, and it didn't help the turmoil that seemed to be affecting his innards, his chest seeming to tighten in response. Maybe he was having a heart attack.

"Finally. I was beginning to think you didn't have any facial expressions," Dean chuckled, reaching over to pat Castiel on the shoulder. Luckily he was still shocked, otherwise the contact might have made him jump. "Don't worry about it. I'm beautiful, I know." He paused in his eating long enough to "flip his hair", a move that finally made Cas smile. Dean's smile seemed to brighten in return, and he stifled another chuckle by finishing off his burger. A few moments of silence passed between them, during which Castiel decided he should say something, anything, when the bell rang.

"I have to return to class," Castiel said, standing suddenly. Dean looked almost surprised before he stood as well, wiping his hands off on his shorts. His rather short…bright red shorts. It would be rude to laugh.

"I'll walk you," Dean said, nodding towards the door before starting off, leaving Castiel to catch up outside the break room. "Science hall, right? Chemistry?" Castiel was surprised he even remembered.

"Yes…room 230 A," he replied, shuffling alongside the P.E. teacher as they made their way upstairs. Dean talked about this and that - which female teachers he found attractive, how annoying yet hilarious kids were – until they reached his door. Castiel hadn't noticed how much he liked listening to Dean talked till he stopped. Dean smiled and reached up, adjusting Castiel's haphazard tie.

"You always so messy? Jesus," he said, apparently either not noticing or ignoring Castiel's surprise, though he was probably just using his "concentration face" again. A moment later he felt Dean pat his shoulder, looking up to see him smile and walk off. "See ya, Cas."

The next few weeks were a dreary daze. They spoke more after that, often sharing lunch, as Castiel tended to bring food Dean enjoyed and eat little of it himself. The days were shorter and colder; Castiel began to bring his trench coat more often, which Dean never mentioned but often looked at. It made Castiel tense, but not in a terribly bad way, he noticed.

It was a Friday after school when Castiel decided to figure this problem out, once and for all. He had started charting equations, mapping out what he wanted to explain and show to Dean. He had decided to tell him about the ache in his chest.

"Do you ever clean this room? It's a fuckin' pigsty," Dean said with his mouth half full, chewing noisily as he stood in the doorway.

Castiel looked at the room. He'd never even seen it that way before. There were papers everywhere; algorithms, partial equations and half-forgotten notes; to-go boxes stacked haphazardly on the edge of the desk; books either heaped on the table or randomly set on the three planks he'd had set up as shelves screwed into the wall; endless cords tangled just beneath his desk, all leading up to a long power strip; extra notes either pinned wherever there was room, or scribbled on two chalkboards he had mounted on the far wall to the left of his books, one of which was mounted with just a bit of overlap on the bottom one and still it reached the ceiling; all this illuminated by his computer monitor and a single strip of halogen embedded down the middle of the ceiling. How he had managed to do any work, he now realized, was a miracle. Even more miraculous was the fact that, on most days, he could find everything he needed. Had his students ever mentioned it? He couldn't recall.

"…I'm sorry," Castiel said, haltingly, after a brief period of silence. Dean shook his head and wandered in, his gaze drifting over the chalkboard.

"So…what's this?" he asked, and Castiel cleared his throat. There really was no turning back now, and he felt a nauseating excitement building in him. His eyebrows drew together as he concentrated, running a hand through his short black hair before finding a place to start.

"This… is the heartbeat cycle," Castiel began, motioning to a graph he'd drawn of a winding backwards 'S' on the x-axis of a graph, with multiple arrows pointing in towards the line. "This equation…the equation of the graph-" His hand drifted over half-missing scribbles and erased numbers. "-here. DX over DT equals the negative total of x cubed minus Tx plus b, where-"

"Cas…" Dean started, but the shorter teacher had built a momentum that couldn't be stopped.

"The resting heart rate is around here, 60 to 90 beats per minute," Castiel continued, pointing to one part of the line, lightly smudging where he'd touched. "But I've found that, when I'm around you, if you plug in the extraneous variables and tweak the calculation somewhat, then you end up with…with a partial equation which can be solved, to which the solution is-"

"Cas."

Castiel paused, looking back at Dean with wide blue eyes, wringing his chalk-covered hands in front of him. "…the solution is: it's very fast."

Everything seemed to slow down now that he was done, nervously licking his cracked lips a moment as he paused, eyebrows furrowed. What had he done? His heart was racing, as he had calculated, but he felt a sort of dread now that he hadn't before.

It seemed to take an eternity until Dean caught up, and when he did, he finally smiled, a small thing that almost resembled a smirk. Perhaps Dean was laughing at him. "You did all that because your heart beats faster around me?" Castiel paused, completely empty from his explanation, and nodded. Dean glanced at the board, shaking his head at what was only gibberish to him spilled out in chalk before slowly walking over to Cas. He reached up, setting his hand just under Castiel's jaw, his fingertips lightly brushing the nape of the chemistry teacher's neck.

"You coulda just said you like me," Dean hummed, and Castiel felt his heart nearly leap out of his chest, something he could not put an equation to.

"I love you," he murmured, slowly closing the gap between them.


End file.
